When I move the viewpoint close to an object, it starts to disappear. How can I disable OpenGLs zNear clipping plane?
You can’t. If you think about it, it makes sense: What if the viewpoint is in the middle of a scene? Certainly some geometry is behind the viewer and needs to be clipped. Rendering it will produce undesirable results. For correct perspective and depth buffer calculations to occur, setting the zNear clipping plane to 0.0 is also not an option. The zNear clipping plane must be set at a positive (nonzero) distance in front of the eye. To avoid the clipping artifacts that can otherwise occur, an application must track the viewpoint location within the scene, and ensure it doesn’t get too close to any geometry. You can usually do this with a simple form of collision detection. This FAQ contains more information on collision detection with OpenGL. If you’re certain that your geometry doesn’t intersect any of the view-volume planes, you might be able to use an extension to disable clipping. See the previous question for more information.
